Fix #119: Detect when using is an identifier

src/typescript/Scala.tmLanguage.ts

@@ -404,7 +404,7 @@ export const scalaTmLanguage: TmLanguage = {
     'using': {
       patterns: [
         {
-          match: `\\(\\s*(using)`,
+          match: `(?<=\\()\\s*(using)\\s+(?=[\\w\\d\\(\\.\\(\\{'"])`,
           captures: {
             '1': {
               name: 'keyword.declaration.scala'

tests/unit/#119.test.scala

@@ -0,0 +1,21 @@
+// SYNTAX TEST "source.scala"
+
+   (using)
+// ^ meta.bracket.scala
+//  ^^^^^ source.scala
+//       ^ meta.bracket.scala
+
+   (using  )
+// ^ meta.bracket.scala
+//  ^^^^^^^ source.scala
+//         ^ meta.bracket.scala
+
+   (using , )
+// ^ meta.bracket.scala
+//  ^^^^^^^^ source.scala
+//          ^ meta.bracket.scala
+
+   (usingSomething)
+// ^ meta.bracket.scala
+//  ^^^^^^^^^^^^^^ source.scala
+//                ^ meta.bracket.scala             

tests/unit/using.test.scala

@@ -7,6 +7,10 @@ def f(using x: Int): Unit = ()
 //  ^^^^^ keyword.declaration.scala
 //        ^ constant.numeric.scala
 
+  f(using .2)
+//  ^^^^^ keyword.declaration.scala
+//         ^ constant.numeric.scala
+
 class A(using x: Int)
 //      ^^^^^ keyword.declaration.scala
 
@@ -21,3 +25,20 @@ given [T](using x: Ord[T], using: Int) as Ord[List[T]]
 
 given [T](using Ord[T]) as Ord[List[T]]
 //        ^^^^^ keyword.declaration.scala
+
+  f(using ())
+//  ^^^^^ keyword.declaration.scala
+//        ^^ meta.parentheses.scala meta.bracket.scala
+
+  f(using {})
+//  ^^^^^ keyword.declaration.scala
+//        ^ punctuation.section.block.begin.scala
+//         ^ punctuation.section.block.end.scala
+
+  f(using ' ')
+//  ^^^^^ keyword.declaration.scala
+//        ^^^ constant.character.literal.scala
+
+  f(using "")
+//  ^^^^^ keyword.declaration.scala
+//        ^^ string.quoted.double.scala